The present invention relates to a non-contact conveyance system for conveying flat objects to be conveyed such as a mother glass substrate and a semiconductor wafer substrate in non-contact.
While numbers of productions of flat panel displays such as liquid crystal displays, plasma displays and touch panel displays are increasing lately, such flat panel displays are also growing in size. Still more, because a cost per panel is determined by a number of panels taken out of one mother glass, i.e., a number of planes that can be taken out, the size of the mother glass substrate is growing year by year. The semiconductor wafer substrates are also being made thinner rapidly. Accordingly, a drop of yield of the thin mother glass substrates and semiconductor wafer substrates caused by damages that occur during their conveyance is posing a problem. Thus, during their conveyance, they require, as preferable conditions, not to be stained, no stress to be applied and no damage to be given.
Hitherto, such substrates are conveyed by way of a contact conveyance method using conveyor rollers, a folk lift and the like. However, when the size of the substrates grows as described above, it is necessary to increase a number of rollers or a number of folks of the conveyor roller, folk lift and the like of the contact conveyance method to alleviate stress applied to the substrates corresponding to the growing size, a considerable amount of works is required to strictly adjust, control and maintain levels of the large number of rollers and folks.
Then, there has been proposed a non-contact conveyance system that levitates an object to be conveyed (referred to as a ‘conveyance object’ hereinafter) on a conveying path by pressure of fluid discharged from the underside by a fluid pressure levitating section and conveys the conveyance object levitated on the conveying path in a predetermined direction by an acoustic viscous flow generated between resilient vibrating plates exciting deflection traveling waves and the surface of the conveyance object (see Japanese Patent Application Laid-open No. 2006-76690 Gazette for example). This non-contact conveyance system is provided with a large number of driving units each composed of the resilient vibrating plate and an exciting actuator and disposed along the conveying path.